# Dynamic Atomistic Polar Structure Underpins Ultrahigh Linear Electro-Optic Coefficient in Transparent Ferroelectric Ceramics

## TL;DR

Researchers created transparent ferroelectric ceramics with an ultrahigh electro-optic coefficient, enabling better performance in electro-optical devices.

## Contribution

A novel fabrication method and chemical design achieved near-theoretical optical transparency and a record-high electro-optic coefficient.

## Key findings

- Transparent ceramics were fabricated with optical transparency near the theoretical upper limit.
- The ceramics exhibit an ultrahigh linear electro-optic coefficient of ∼1417 pm/V, over 65 times higher than LiNbO3.
- Dynamic atomistic polar structures in domains enhance electronic polarization sensitivity.

## Abstract

Transparent ferroelectrics
with high linear electro-optic
(EO)
coefficients are critical for advanced electro-optical devices. However,
achieving optical transparency in ferroelectric ceramics remains challenging
due to visible light scattering caused by defects such as domain walls,
grain boundaries, and pores. Here, we report the successful fabrication
of transparent ferroelectric ceramics through innovative chemical
composition design and an advanced two-step sintering process in the
La-doped Pb­(Mg1/3Nb2/3)­O3–PbTiO3 system. The optical transparency, which is near the theoretical
upper limit, can be attributed to the wide band gap and the minimization
of light scattering of defects. By minimizing porosity and engineering
grain/domain sizes to differ significantly from the wavelengths of
visible light, we suppress scattering, achieving optical transparency
near the theoretical upper limit. Strikingly, these ceramics exhibit
an ultrahigh linear EO coefficient of ∼1417 pm/V, over 65 times
greater than that of LiNbO3 single crystals, the current
industry standard. We attribute this exceptional performance to dynamic
atomistic polar structures within switchable, thermally stable domains,
which enhance electronic polarization sensitivity. This mechanism
is corroborated by dielectric spectroscopy, high-resolution transmission
electron microscopy and simulation. Our findings offer insights into
the design of cost-effective transparent materials with exceptional
EO properties, paving the way for next-generation electro-optical
devices.